Originally Posted by xfuego
I make computer chips for a living and I have absolutely no idea how 'piggybacking" a chip onto another chip would do anything good. The best scenario is that it would make no difference at all (putting a dead chip on a good chip) OR, you blow the good chip up.
The theory behind the piggyback is that it intercepts and modifies signals that are to be sent to the ECU. The same theory as a firewall in a computer network which strips out objectionable material. There are actually a lot of very reputable companies that make piggybacks, but they're pretty pricey.